1. Field
One or more embodiments described herein relate to a compressor.
2. Background
Generally, a compressor used in a refrigerator, an air conditioner, etc. has a configuration that a compression part for sucking and compressing a refrigerant is installed below a casing, and a motor part is installed above the compression part. The compression part and the motor part are connected to one shaft. Under this configuration, the shaft is rotated by a driving force generated through the motor part. By the rotation of the shaft, the compression part coupled to the shaft is driven to perform a compression operation.
In order to smoothly rotate the compression part, oil has to be supplied to bearing, a rolling piston, etc. of the compression part. Generally, the oil is stored at a lower part of a casing, and is pumped by an oil feeder installed at a lower end of the shaft to be supplied to the compression part. The oil serves not only to perform a lubrication operation, but also to cool the motor part. Therefore, for an enhanced lifespan and efficiency, control of a proper amount of oil to the compressor should be stably supplied.
One type of compressor is configured to be driven at a constant speed in a normal driving mode. Accordingly, a proper amount of oil can be supplied to the compressor only if a proper amount of oil is supplied into a casing, in a condition that the compressor is not mechanically damaged or mal-operated. For an efficient driving, a compressor capable of having an increased or decreased operating speed is being widely used. As a representative example of the compressor, there is provided a compressor having a BrushLess Direct Current (BLDC) motor.
In case of this BLDC motor, acceleration is irregularly increased and decreased during an operation. This irregular increment or decrement may influence on a level of oil stored at a lower portion of a casing. This may temporarily lower an oil level according to changes of the operating speed even in a state that the casing is supplied with a proper amount of oil therein. As a result, oil may not be smoothly supplied into the compression part. This may lower the efficiency and shorten the lifespan of the compressor.